Electric circuit safety lock



March 4, 1930. w. 'w. SLOANE ELECTRIC CIRCUIT SAFETY LOCK Filed Dec. 31, 1927 @rmy Patented Mar. 4, 1930 UNITED. STATES PATENT OFFICE WILLIAM SLOANE, OF CHICAGO, ILLINOIS, ASSIGNOR TO GOODMAN MANUFACTUR- ING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS as i ELECTRIC CIRCUIT SAFETY LOCK Application filed December 31, 1927.

My invention relates to electric circuits involving removable circuit connections such as overload fuses and has for its general object the provision of means whereby a removable circuit connection such as a fuse stood by reference to the accompanying drawing, in which:

Figure 1 is a top plan view of electric circuit means embodying my invention with parts broken away and in section;

Figure 2 is a front elevation of the same with parts broken away;

Like numerals refer to like parts in the several views.

Referring to the drawing, 1 designates a casing enclosing therein an electric switch including stationary contacts 2 and movable contacts 3 secured upon a pivoted shaft 4 for angular movement into and out of engagement with the contacts 2. The shaft 4 extends forwardly and rearwardly and angularly secured with the front end of the shaft 4 is an operating arm 5 extending exteriorly of the casing for the manual operation of the switch.

Formed with the casing 1 at one end .thereof is an enclosure or fuse box 6 the front of which is open to provide an access opening. Hinged to the casing 1 on a vertical axis, as designated at 7, for movement into and out of position closing the access opening of the fuse box is a cover 8, a marginal tongue and groove labyrinth engagement 9 being provided between the cover 8 and the fuse box when the cover is in closed position to prevent any arcing that might occur in the fuse box from igniting explosive gas on the exterior of the fuse box.

Hinged to the casing 1 on a vertical axis, as designated at 11, disposed at the side of the fuse box opposite that on which the hinge Serial No. 243,886.

7 of the cover is disposed and inwardly of the plane of the cover when in closed position is a locking member 12. The main portion of the locking member 12 is roughly of U-shape and the intermediate portion thereof is disposed parallel with the axis, so that in the angular movement of the same the said intermediate portion may be positioned in overlying relation with radial extensions 13 on the free end of the cover 8 to lock the cover in closed position or may be moved out of overlying relation with the extensions 13 to unlock the cover for the movement of the cover into open position. The cover locked position, the locking member and cover is shown in Figures 1 and 2, and the unlocked position of the locking member and the open position of the cover is shown in broken lines in Figure 1.

The intermediate portion of the locking member 12 is provided With a concave surface formation 14 which is engageable with the free end of the arm 5 when this arm is in closed circuit position to prevent unlocking movement of the locking member. When the arm 5 is in open circuit position the surface formation 14 is not engageable with the arm 5 so that the locking member 12 may be moved to unlocked position for the opening of the cover 8 when the switch is in open circuit position. The closed circuit position of the arm 5 is shown in full lines and the open circuit position thereof is shown in broken lines in Figure 2.

The locking member 12 is provided with a lateral extension 15 at its lower end which overlies the free end of the arm 5 when the arm 5 is in open circuit position and the locking member 12 is in unlocked position to prevent the switch being closed while the locking member 12 is in unlocked position.

The intermediate portion of the locking member 12 is provided with an extension arm 16 which extends toward the hinge 7 of the cover 8 in overlying relation with the cover when the cover is closed and the locking member in position locking the same. The opening movement of the cover 8 is limited by stop lugs 17 thereon engaging the adjacent face of the fuse box, and when the cover is in open position the locking member 12 cannot be moved into locking position, where the extension 15 releases the arm 5 for movement into closed circuit, by reason of the fact that the extension arm 16 engages the cover 8 to prevent the movement of the locking member 12 into locked position, as shown 1n broken lines in Figure 1.

As a result the cover 8 cannot be opened except when the switch is in open circuit position, and the switch cannot be closed until the cover is closed and locked.

Thus a fuse 18 cannot be removed from or replaced on a fuse mounting 19 within the fuse box 6 unless the switch is in open circuit position and the switch cannot be closed until the cover 8 is closed, and the switch being in circuit with the fuse mounting the circuit must be open when a fuse-is renewed or replaced and the cover 8 must be closed in order to close the circuit.

While I have shown herein and described one form of my invention, I do not wish to be limited to the precise details'of construction or arrangement of parts herein shown and described except as specifically limited in the appended claims.

1 claim as my invention:

1. In a device of the character described,

the combination with a pivoted electric switch member, of a cover locking member pivotally mounted on an axis transverse to and spaced from the axis of said switch member for movement into and out of locking position,

-;and a concave surface formation on said lockmg member and extending axiall thereof and engageable with the ree en of said switch member to prevent movement of said locking member out of locking osition while said switch member is in close circuit posi-' tion.

2. In a device of the character described, the combination with a pivoted electric switch operating arm, of a cover locking member pivotally mounted on an axis transverse to and spaced from the axis of said arm for movement into and out of locking position, a concave surface formation on said locki member and extending axially thereof aiid ;engageable with the free end of said switch member to prevent movement of said look ing member out of locking position while said switch member is in closed position, and a stop formation on said locking member at an .end of said concave formation and facing axially of said locking member and away from said concave formation and engageable with said arm to prevent movement of the same into circuit closin position while said locking member is out 0 locking position.

3. In a device of the character described, the combination with a pivoted electric switch member, of a cover locking member of U-shape pivotally mounted by means of the legs thereof on an axis transverse to and 4. In a device of the character described,

the combination with a pivoted electric switch operating arm, of a cover locking member of U-shape pivotally mounted by means of the legs thereof on an axis transverse to and spaced from the axis of said switch member for movement into and out of locking position, a concave surface formation on the intermediate portion of said locking member and extendin axially thereof and engageable with the free end of said arm to prevent movement of said locking member out of locking position while said arm is in closed circuit position, a stop formation on said locking member at an end of said concave formation and facing axially of said locking member and away from said concave formation and engageable with said arm to prevent movement of the same into circuit closing position while said locking member is out of locking position, and an arm on the intermediate ortion of said locking member and exten in therefrom for preventing movement of sai locking member into locking position when 'a pivoted cover associated therewith is in 

